Full virtualization

In computer science, full virtualization (fv) employs techniques used to create instances of an environment, as opposed to simulation, which models the environment; or emulation, which replicates the target environment such as certain kinds of virtual machine environments. Full virtualization requires that every salient feature of the hardware be reflected into one of several virtual machines – including the full instruction set, input/output operations, interrupts, memory access, and whatever other elements are used by the software that runs on the bare machine, and that is intended to run in a virtual machine. In such an environment, any software capable of execution on the raw hardware can be run in the virtual machine and, in particular, any operating systems. The obvious test of full virtualization is whether an operating system intended for stand-alone use can successfully run inside a virtual machine. This is a modern technique developed in late 1990s and is different from simulation and emulation. The cornerstone of full virtualization or type-1 virtualization is a hypervisor or Super Operating system that operates at a higher privilege level than the OS. This Hypervisor or Super OS requires two key features to provision and protect virtualized environments. These two features are: OS-Independent Storage Management to provision resources for all supported Virtual Environments such as Linux, Microsoft Windows or embedded environments and to protect those environments from unauthorized access and, Switching of Virtualized environments to allocate physical computing resources to Virtual Environments. See Intel VT-x or AMD-V for a detailed description of privilege levels for Hypervisor, OS and User modes, VMCS, VM-Exit and VM-Entry. This virtualization is not to be confused with IBM Virtual Machine implementations of late 60's and early 70's as IBM systems architecture supported only two modes of Supervisor and Program which provided no security or separation of Virtual Machines.

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Concepts associés (15)

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Virtualisation

La virtualisation consiste, en informatique, à exécuter sur une machine hôte, dans un environnement isolé, des systèmes d'exploitation — on parle alors de virtualisation système — ou des applications — on parle alors de virtualisation applicative. Ces ordinateurs virtuels sont appelés serveur privé virtuel (Virtual Private Server ou VPS) ou encore environnement virtuel (Virtual Environment ou VE).

Comparison of platform virtualization software

Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic information about platform virtualization hypervisors. Providing any virtual environment usually requires some overhead of some type or another. Native usually means that the virtualization technique does not do any CPU level virtualization (like Bochs), which executes code more slowly than when it is directly executed by a CPU.

Full virtualization